Thread socketServerThread=new Thread(new ServerSocketThread());
        socketServerThread.start();

public class ServerSocketThread extends Thread {
    static final int SocketServerPORT = 8080;
    int count = 0;

    @Override
    public void run() {
        try {
            serverSocket = new ServerSocket(SocketServerPORT);

            Toast.makeText(getApplicationContext(), "server is on", Toast.LENGTH_SHORT).show();

            while (true) {
                Socket socket = serverSocket.accept();

            }
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}

04-11 21:57:23.864: E/AndroidRuntime(11761): FATAL EXCEPTION: Thread-11
04-11 21:57:23.864: E/AndroidRuntime(11761): java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
04-11 21:57:23.864: E/AndroidRuntime(11761):    at android.os.Handler.<init>(Handler.java:121)
04-11 21:57:23.864: E/AndroidRuntime(11761):    at android.widget.Toast.<init>(Toast.java:68)
04-11 21:57:23.864: E/AndroidRuntime(11761):    at android.widget.Toast.makeText(Toast.java:231)
04-11 21:57:23.864: E/AndroidRuntime(11761):    at com.example.imagesender.MainActivity$ServerSocketThread.run(MainActivity.java:79)
04-11 21:57:23.864: E/AndroidRuntime(11761):    at java.lang.Thread.run(Thread.java:1019)

public void run() {
    // custom thread actions
    mActivity.runOnUiThread(new Runnable() {
        public void run() {
            // code that should be run on UI Thread
        }
    });
    // custom thread actions
}